2) Killing Floor 2

Killing Floor 2 Gameplay

If you’ve played Nazi Zombies in COD, then you’ll be very familiar with Killing Floor 2. It’s sort of like a tower defense co-op game where you and friends fight against waves of zombies while running across a map, and at the end of the waves you get to fight a boss.

Even after the waves of enemies stop, bosses keep coming!

Any horde can be taken down with a double barrel.